Electrophotographic copying machine

ABSTRACT

An electrophotographic copying machine which includes a housing, an original holder reciprocable upon the upper surface of an electrophotographic photosensitive member unit that includes an electrophotographic photosensitive member mounted for rotation at substantially the center of the housing. Charging apparatus is mounted on one side of the electrophotographic photosensitive member and an optical system for effecting exposure through a slit and developing apparatus is provided. Fixing apparatus and cleaning apparatus are disposed on the other side of the electrophotographic photosensitive member. Copy medium feeding elements and image transfer members are disposed below the electrophotosensitive member, and the electrophotosensitive member unit is mounted in the housing so as to be removable upwardly therefrom.

Ito et al. 1 1 May 13, 1975 [541 ELECTROPHOTOGRAPHIC COPYING 3.438.7064/1969 Tanaka et a]. 3 355 14 x $575,139 4/l97l NuZum .1 .1 118/637MACHINE 1626.898 l2/l97l Gawron 118/637 [75 1 Invemms' FOREIGN PATENTSOR APPLICATIONS Masaru Yamaguchi Yokohama France 1 v y v 1 r r r r 1 r rof Japan Primary E.ruminer-Richard A. Wintercorn [73] ASS'gnee: CanonKahush'k' Kalsha Tokyo Armrney, Agent or Firm-Fitzpatrick. Celia. HarperJapan & Scinto [22] Filed: Apr. 5, 1973 [21] Appl. No.; 348,093 [57] PAn electrophotographic copying machine wh1ch |n- Relaled pp Dam cludes ahousing, an original holder reciprocable upon [62] Division of Ser, N120,132 M h 2 1971, P r, the upper surface of an electrophotographicphotosen- No 3,784,297. sitive member unit that includes anelectrophotographic photosensitive member mounted for rotation [30]Foreign Application Priority Data at substantially the center of thehousing Charging ap- Man 1] 1970 Japan M 45 20075 paratus is mounted onone side of the electrophoto- Apt |5y [970 japan 45 32| 12 graphicphotosensitive member and an optical system for effecting exposurethrough a slit and developing 52 US. (:1 355/3 on; 117/115; 118/637apparatus is provided- Fixing apparatus and Cleaning [51] Int. Cl r.G03g 15/00 apparatus are disposfid the Other Side Of the elec- [58]Field of Search 355/3 DD; 118/637; trophowgraphic photosensitivememberpy 17/17 5; mg 1 dium feeding elements and image transfer membersare disposed below the electrophotosensitive member, [56] References Cid and the electrophotosensitive member unit is mounted UNITED STATESPATENTS in the housing so as to be removable upwardly there 3,333 5668/1967 Kent 355/3 DD from. 3 358.63? 12/1967 Shearer et a1 118/7 5Claims, 44 Drawing Figures Llll PATENTEUHAY 1 slrs q 883 240 saw near 16Fh-JENTEU HAY I 31975 3, 883.240

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F'ATENTEU HAY 1 3 i975 SHEET CBUF 16 PMENTED HAY 1 31975 3, 883 240SHEET 10 0F 16 PHENTEU HAY 1 BISYS SHEET llUF 16 FIG. 24

PATENIEDMAY 1 3:975 3,883,240

saw 120; 16

FIG. 25

PATENTED m 1 31915 3,883 .240

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SHEET lSUF 16 FlG. 35(A) ELECTROPHOTOGRAPIIIC COPYING MACHINE This is adivision, of application Ser. No. 120,132, filed 3/2/7l, now U.S. Pat.No. 3,784,297 issued 1/8/74.

BACKGROUND OF THE INVENTION I. Field of the Invention The presentinvention relates to a photocopying machine and more particularly anelectrophotographic copying machine of the type in which an originalstand is reciprocated, exposure is made through a slit and anelectrophotographic photosensitive member is in the form of a rotarydrum. More specifically the present invention relates to anelectrophotographic copying machine of the type in which anelectrophotographic pho tosensitive member consisting of aphotoconductive photosensitive member consisting of a photoconductivelayer sandwiched between an insulating surface layer and an insulatingor conducting member is used and an original in the form ofa sheet or athick original may be reproduced automatically. rapidly and economicallyreproduced upon copy media such as sheets of copy paper or the like (tobe referred to as copy pa' per" hereinafter in this specification).

2. Description of the Prior Art In general, inthe electrophotographiecopying machines available in the market, both of ordinary sheets ofpaper and photosensitive sheets are used for reproducing an original inthe form ofa sheet or a thick original. The reproduction cost is high inthe electrophotographic copying macine of the type using photosensitivesheets. Therefore the electrophotographic copying machines of the typeusing paper sheets are widely used because the cost per copy is verylow, However, the electrophotographic photosensitive members which arerepetitively used must be replaced when it is damaged. The advantages ofthe electrophotographic copying machines of the type using paper sheetswill be cancelled if the replacement of the electrophotographicphotosensitive members is difficult or the readjustment of theelectrophotographic copying ma chines is required after the replacement.

SUMMARY OF THE INVENTION One of the objects of the present invention isto provide an improved electrophotographic copying machine (to bereferred to as photocopying machine" for brevity hereinafter) which iscompact in size because a space required for replacement of anelectrophotographic photosensitive member (to be referred to assensitive member or drum for brevity hereinafter) may be reduced to theminimum and which facilitates the inspection and maintenance of variousmenas required for the electrophotographic process and disposed aroundthe sensitive drum or member after its removal.

Another object of the present invention is to provide an improvedphotocopying machine in which various processing means are arranged asunits so that the mounting or removal and inspection and maintenance ofthese various units may be much facilitated.

According to the present invention there is provided an improvedphotocopying machine in which an original holder upon which is placed anoriginal to be copied is disposed upon the top of the photocopyingmachine for reciprocal movement and the copy papers are fed one by oneby feeding means and discharged after the copying operation.

At the center of the main body of the housing is dis posed a rotarysensitive drum to the peripheral surface of which is applied alamination consisting of a photoconductive layer sandwiched between aninsulating surface layer and an insulating or conducting layer. Aroundthe sensitive drum are disposed first charging means, simultaneousexposure-charging means, whole-surface-illumination means, developingmeans, third charging means, image transfer means and cleaning means inthe order named in the direction of rota tion of the rotary sensitivedrum.

The rotary sensitive drum is positively or negatively charged by dccorona discharge generated by the first charging means. The dc coronadischarge whose polarity is opposite to that of the dc corona dischargeby the first charging means or ac corona discharge is applied to therotary sensitive drum by the simultaneous exposure-charging meanssimultaneously when a light or radiation image of the original to bereproduced is exposed or projected upon the rotary sensitive drum. Bythe wholesurface exposure means, the whole surface of the rotarysensitive drum is uniformly exposed so as to increase the contrast ofthe image. The electrostatic latent image thus formed may be developedinto a positive or negative toner image by the toner which is chargedwith a polarity opposite to or same as that of the latent image by thedeveloping means. The third charging means is not necessarily required,but may be used with a desired polarity so that the image transferefficiency may be improved. The toner image thus developed may betransferred by the image transfer means to a copy paper. After the imagetransfer the toner which still remains upon the rotary sensitive drum isremoved or cleaned by the cleaning means. Thus one cycle of copying orreproduction operation is completed as far as the rotary sensitive drumis concerned. The copy paper is separated from the rotary sensitive drumby a separating means and fixed in the fixing means and then dischargedout of the photocopy ing machinev BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 is a perspective view illustrating the outer apperance ofaphotocopying machine in accordance with the present invention;

FIG. 2 is a longitudinal front view thereof;

FIG. 3 is a transverse sectional view thereof; illustrating a rotarysensitive drum unit and a reciprocable orig inal holder;

FIG. 4 is a top view of the rotary sensitive drum unit;

FIG. 5 is a perspective veiw of the original holder and itsreciprocating means,

FIG. 6 is a perspective view illustrating the mounting and removal ofthe rotary sensitive drum unit;

FIG. 7 is a view illustrating the mounting and removal of means forilluminating the original and charging means unit;

FIG. 8 is a sectional view of a developing means;

FIG. 9 is a perspective view illustrating means for supplying thedeveloping agent to the developing means;

FIG. 10 is a fragmentary front view thereof on en- Iarged scale;

FIG. 11 is a side view thereof;

FIG. 12 is a top view of means for circulating the developing agent inthe developing means;

FIG. 13 is a longitudinal front view of another embodiment of means forsupplying the developing agent in accordance with the present invention;

FIG. 14 is a side view thereof;

FIGS. 15 and 16 are side views illustrating one embodiment of means foropening or closing a discharge opening of a hopper;

FIGS. 17 and 18 are front view illustrating means for adjusting an angleof rotation of a spiral feed roller disposed in the hopper shown inFIGS. 15 and 16;

FIG. 19 is a perspective view of the opening and closing means shown inFIGS. 15 and 16;

FIG. 20 is a front view of one embodiment of a passage of copy paper;

FIG. 2] is a fragmentary perspective view thereof on enlarged scale;

FIG. 22 is a front view of one embodiment of means for controlling theactivation and de-activation of the developing means;

FIG. 23 is an electric circuit diagram thereof.

FIG. 24 is a perspective view of one embodiment of fixing means inaccordance with the present invention;

FIG. 25 is a front view thereof;

FIG. 26 is a longitudinal view thereof;

FIG. 27 is a sectional view of one embodiment of cleaning means inaccordance with the present invention;

FIG. 28 is a fragmentary top view thereof on enlarged scale;

FIG. 29 is a sectional view of another embodiment of cleaning means inaccordance with the present invention;

FIGS. 30, 31, 32(A), 32(8) and 33 are views illustrating brushes used inthe cleaning means for removing the developing agent;

FIG. 34 is a view illustrating one embodiment of means for moving thedeveloping agent removed in the cleaning means to a collection box;

FIGS. 35(A) through 35(D) are an illustration of a method for applyingon and removing from a roller a cleaning material in accordance with thepresent invention;

FIG. 36 is a front view illustrating means for controlling the rotationof a cleaning roller;

FIG. 37 is a sectional view thereof;

FIG. 38 is a longitudinal view of one embodiment of charging means inaccordance with the present invention;

FIG. 39 is a top view thereof; and

FIG. 40 is a transverse sectional view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I shows a perspective viewof an embodiment of the present invention showing its outer apperance.Upon an original holder 1] is placed an original with its surface faceddown. The original holder II is reciprocated for carrying the slitexposure. The sheets of copy paper P are fed one by one by a feedingmeans, processed by an electrophotographic device and discharged out ofan outlet 12.

Referring to FIG. 2, upon the peripheral surface of a drum 2 rotating inthe direction indicated by the arrow is formed an electrophotographicsensitive layer 1 consisting ofa photoconductive layer sandwichedbetween a surface insulating layer and a conducting or insulating layer.Around the rotary drum 2 are disposed in the order named a firstcharging means 3, a simultaneous exposure-charging means 5, awhole-surface exposure means 6, a developing means 7, a third chargingmeans 8, a transfer means 9 and a cleaning means l0.

The DC corona discharge is imparted by the first charging means 4 to thesurface of the rotary sensitive drum 2 so that the sensitive layer 3 maybe positively or negatively charged. By the simultaneousexposurecharging means 5 the DC corona discharge having the polarityopposite to that applied by the first charging means 4 or the AC coronadischarge is applied to the sensitive layer 3 simultaneously when alight or radia tion image of the original to be copied is projected uponthe sensitive layer 3 or drum 1 to produce an electrostatic image.

Thereafter by the whole-surface exposure means 6 such as fluorescentlamp the electrostatic latent image is uniformly illuminated so as toincrease the action of the latent image as the external field, therebyincreas ing the contrast of the electrostatic latent image. By use ofthe toner having the polarity opposite to that of the electrostaticlatent image. it is developed by the devel oping means 7. Alternatively,the electrostatic latent image may be developed into a negative image byuse of the toner having the same polarity as that of the latent image.It is preferable to use the magnet brush or fur brush developing method.

The third charging means 8 is not necessarily required. However. it isused with a suitable polarity so as to improve the efficiency oftransferring to the copy paper P the toner image formed upon thesensitive drum 1. The toner image is transferred electrostatically tothe copy paper I by the transfer means 9. The toner still remained uponthe sensitive drum 1 after the image transfer is wiped off by cleaningrollers in the cleaning means 10.

The copy paper P upon which is transferred the toner image from thesensitive drum 1 is separated from the sensitive drum by a separatingmeans, fixed by the fixing means and discharged out of the photocopyingmachine from the outlet 12. Since the copy paper P is charged, theelectrostatic charge is removed from the copy paper P by an AC chargingmeans 30.

In addition to the means described above, the photocopying machine inaccordance with the present invention further includes driving means,exposure means, feeding means. control means and so on and the pres entinvention is characterized by the arrangement thereof and the assemblyand disassembly thereof as will be described in more detail hereinafter.

ORIGINAL HOLDER AND DRIVING MEANS As shown in FIG. 3, the originalholder II has two rollers 17 and 18. The roller 17 rides on a rail 13extending between frames of the housing while the roller 18 is enclosedin a channel-like member 16 and rides on a rail 14 mounted between theframes. It is noted that the rail 14 and the roller 18 in the channellike member 16 are disposed below an inner frame 15 of the originalholder 11. The deviation in the transverse direction, that is to theright and left of the original holder ll may be prevented by the roller18 which has a configuration ofa drum as shown in FIG. 3 while thevertical deviation may be prevented by the combination ofa rollervertically movably fixed to the channel- Iike member 16 and made incontact with the undersurface of the rail 14 under the force of a spring20 loaded between the lower roller 19 and the upper roller I8. Atransparent plate 21 such as a glass plate is mounted on the inner frameof the original holder 11 and a pressure plate 22 for pressing theoriginal against the transparent plate 21 is provided.

Still referring to FIG. 3, a shaft 27 of the sensitive drum 1 extendingthrough bearings 23 of end plates I and I is supported by supportingplates 25 and 25 and retained by retaining members 26 and 26 Stays 24are fixed to the supporting plates 26 and 26 which in turn are fixed toside plates 3I and 31 fixed to the housing. A driving gear 30 is mountedon a boss of the sensitive drum 1. Thus, the sensitive drum unit isconstituted.

A drive gear G for driving the sensitive drum unit is provided with acontrol member CAM l which is associated with a switch MS-I mounted uponthe side plate 31 for controlling the original holder, a counter and thetoner supply.

Ridges 33 are formed on the supporting plates 25 and 25 while theirmating grooves 32 are formed in the side plates 3I, and 31 as shown inFIGS. 4 and 6 so that the drum unit may be easily, rapidly andvertically mounted on or removed out of the side plates 31 and 31 Thedrum unit may be securely held in position by means of setscrews 34.

The sensitive drum 1 is driven by an electric motor MT through a gear Gan idler G and the drive gear G carried by the drum shaft 27. Thesensitive drum 1 is always rotated in a predetermined direction inoperation.

The original holder 11 is moved in the direction indicated by the arrowa in FIG. 2 when the exposure is made, and upon completion of theexposure the original holder 11 is reversed in the direction of thearrow 1) to the initial position. For this purpose, two belts or wires35 and 36 are wrapped around a guide pulley R and a drive pulley PL inthe opposite directions. One ends of the belts or wires 35 and 36 arefixed to the channel-like member 16 while the other ends to the drivepulley PL. In order to make one reciprocation of the original holder inone cycle operation, two clutches C-1 and C-2 are provided as shown inFIG. 4.

In response to a signal from a start button, the main motor MT starts torotate the sensitive drum 1 through the gears G G and G When the switchMS-] is actuated by the control member CAM-l of the gear G carried bythe sensitive drum 1, the clutch C1 is actuated so as to transmit thepower from the main motor MT to a drive gear G,. through the gears G Gclutch C-l, and a gear G The drive gear G is carried by a shaft 37 whichalso carries the pulley PL. Therefore the drive pulley 37 rotates in thedirection of the arrow C in FIG. 5, winding the wire 35 while unwindingthe wire 36. As a consequence. the original holder 11 is moved in thedirection indicated by the arrow a at a predetermined speed, so that theoriginal is exposed through a slit and the light image is continuouslyprojected upon the sensitive drum 1 through the simultaneousexposure-charging means 5. As a consequence, an electrostatic latentimage is formed upon the sensitive drum 1 which has been previouslycharged by the first charging means 4.

The peripheral speed of the sensitive drum 1 relative to the speed ofthe original holder 11 in the direction of the arrow a is predetermined.Upon completion of the going stroke of the original holder 11, a strokecam CAM-2 (See FIG. 4) mounted upon the drive gear 0,, actuates amicroswitch MS-3 fixed upon the housing so that the clutch O1 isdisengaged while the clutch C-2 is engaged. Whereas the sensitive drum 1rotates in the same direction, the original holder 11 is returned to itsinitial position in the direction indicated by the arrow b by the geartrain ofG G G G the clutch C-2, G and G In this case, the originalholder II may be returned quickly when the number of teeth of the gear Gwhich is in mesh with the gear G used in the return stroke of theoriginal holder I1 is less than that of the gear used in the goingstroke. Thie quick return stroke permits the high speed copyingoperation.

When the original holder 11 returns to its initial posi tion, the strokecam CAM-3 of the drive gear G actuates a microswitch MS-2 (See FIG. 4)so that the main motor MT is temporarily applied with brake so as tostop the original holder II. A short time after the original holder IIhas been stopped, the clutch C-2 is disengaged so that the originalholder 11 is completely disconnected from the main motor MT so that theoriginal holder 11 may be held in its initial position. Simultaneouslythe sensitive drum 1 is also stopped. The above described two-stepoperation of first stopping the original holder 11 and thendisconnecting it from its driving means is employed to absorb theinertia of the original holder in its return stroke.

EXPOSURE MEANS As shown in FIGS. 2 and 7, an illumination system 40includes a light source such as fluorescent lamps 41 for illuminatingthe original, shielding plates 42 and cooling means such as a fan (notshown) which is used for cooling the lamps 41 so as to prevent thedecrease of its illumination efficiency.

The cooling air from the fan is directed in the longitudinal directionofa space defined by the original holder 11, the shielding plates 42 anda black box 43 so that the fluorescent lamps 41 may be cooled alongtheir entire lengths. When the fluorescent lamps 41 are turned on forexposure, a current twice the rated current is supplied to increase theluminous intensity. However, when no exposure is made, the lamps 41 arenormally turned on by the rated current so that there may be nowarming-up time and that its service life may be increased.

Light reflected by the original passes through a transparent plate 45retained in position by a retaining member 44 for preventing the dust orthe like from entering the black box 43 and is re-directed by a firstreflecting mirror 46 inclined at 45 relative to the horizontal linetoward an in-mirror type lens 47. The in-mirror type lens 47 has such aconstruction that the conventional lens is divided into two parts alongits symmetrical axis and a mirror 48 is disposed at the center so thatlight reflected by the second mirror 48 may pass through the lens 47 anda transparent plate 49 for preventing the dust or the like from enteringthe black box 43 and may be projected upon the sensitive drum 1 throughan opening of the simultaneous-exposure-charging means 5. A conductingtransparent plate such as NESA glass may be used as the dust-prooftransparent plate 49 so that the charging efficiency of the simultaneousexposure-charging means 5 may be improved.

As shown in FIG. 2, a reflector 50 for the lamp 41 is partly cut away sothat the intensity of light from a portion of the lamp 41 having noreflector may be reduced,

1. An electrophotographic copying machine comprising a housing, anoriginal holder reciprocable upon the upper surface of anelectrophotographic photosensitive member unit comprising anelectrophotographic photosensitive member disposed substantially at thecenter of said housing and supporting means for rotatably fixing saidmember, charging means disposed on one side of said electrophotographicphotosensitive member, an optical exposure system located to one side ofsaid electrophotographic photosensitive member for effecting an imageexposure through a slit, developing means, fixing means, cleaning means,said fixing and cleaning means being disposed on the other side of saidelectrophotographic photosensitive member, copy medium feeding means,and image transfer means, both of which are disposed below saidelectrophotographic photosensitive member, said electrophotographicphotosensitive member unit being mounted in said housing so as to beremoved upwardly therefrom.
 2. A photocopying machine as defined inclaim 1 wherein said developing means includes a container for storing adeveloping agent, two magnet brushes rotatably fixed between side platesof said developing means, doctor blades for defining the diameters ofsaid magnet brushes, and two mixing rolls which are disposed one bothsides of a partition wall and rotate in the opposite directions so as totransport the developing agent, said mixing rolls being provided withright- and left-handed screws, said partition wall having an openingthrough which the toner flows, said opening being located in such aposition where said right- and left-handed screw threads meet.
 3. Aphotocopying machine as defined in claim 2 wherein said opening is sodefined that the flow rate of the toner through said opening is lessthan the quantity of the toner fed by said mixing rollers.
 4. Aphotocopying machine as defined in claim 2 wherein said developing meansfurther includes means for replenishing the developing agent, saidreplenishing means includes a hopper at the bottom of which is disposeda feed screw or spiral roller and means for intermittently driving saidfeed screw, and said hopper further includes a mixing member inengagement with said screw or spiral feed roller for intermittentrotation, and the developing agent is supplied into said developingagent container having a supply opening formed in the top wall thereof.5. A photocopying machine as defined in claim 4 wherein said opening ofsaid developing agent container is opened and closed in response toopening and closing of a discharge port of said hopper.